Time-reversal switching responses in antiferromagnets

TL;DR

This paper introduces the concept of magnetic toroidal monopoles in antiferromagnets, revealing how they enable novel control of magnetic structures via external electric and magnetic fields, with potential for experimental realization.

Contribution

It proposes emergent time-reversal switching responses in antiferromagnets driven by magnetic toroidal monopoles, a new scalar quantity distinct from known monopoles.

Findings

Magnetic toroidal monopoles enable control of antiferromagnetic structures.

External fields can switch vortex and chirality in antiferromagnets.

Identifies symmetry conditions and candidate materials for experimental observation.

Abstract

We propose emergent time-reversal switching responses in antiferromagnets, which is triggered by an accompanying magnetic toroidal monopole, i.e., time-reversal odd scalar distinct from electric and magnetic monopoles. We show that simple collinear antiferromagnets exhibit unconventional responses to external electric and/or magnetic fields once magnetic symmetry accommodates the magnetic toroidal monopole. We specifically demonstrate that the emergence of the magnetic toroidal monopole in antiferromagnets enables us to control rotational distortion by an external magnetic field, switch vortex-type antiferromagnetic structure by an external electric field, and convert right/left-handedness in chirality by a composite electromagnetic field. We also present the symmetry conditions to induce the magnetic toroidal monopole and exhibit candidate materials including noncollinear antiferromagnets in order to stimulate experimental observations.